1. Field
The present disclosure relates to a wireless communication system, specifically to a method and system for handling a wireless communication in a Voice over Wireless Fidelity (VoWiFi) system.
2. Description of Related Art
Voice over Long Term Evolution (VoLTE) has been widely accepted as the standard mechanism for delivering voice services over an IP Multimedia Subsystem (IMS). Voice over Wi-Fi (VoWiFi) complements VoLTE. Both rely on the IMS framework as a backbone. VoWiFi extends the scope of VoLTE scope to Wi-Fi. The demand for VoWiFi solutions has increased based on benefits to both users of an electronic device (e.g., smartphone, laptop or the like) and mobile operators. A user of an electronic device obtains a better service experience even in indoor and low mobile coverage areas without compromising security. For example, the VoWiFi is operated based on a subscriber identity module (SIM) credential authentication. Mobile operators can expand their customer base to remote areas and gain an edge over existing VoIP solutions by offering VoWiFi services which include security.
FIG. 1 illustrates a call drop scenario during a VoWiFi to VoWiFi (W2W) handover scenario, according to the related art. In FIG. 1, the electronic device 100 is not within an LTE coverage area 300.
The transition between these complementary services of the VoLTE and the VoWiFi is referred to as handover and conventionally represented as VoLTE to VoWiFi (i.e., L2W) and VoWiFi to VoLTE (i.e., W2L). The trigger point for the handovers is determined by the electronic device 100 based on certain parameters. In an example for a typical electronic device 100, the handover criterion is Wi-Fi Received Signal Strength Indicator (RSSI) signal strength alone. However, some solutions propose using other parameters like Real-Time Transport Protocol (RTP) packet loss rate, jitter (a measure of variability of observed packet timing in the context of RTP), or round trip delay. Even though L2W and W2L handovers are addressed in some current implementations, there is no solution available for VoWiFi to VoWiFi (W2W) handovers. Hence, if the user of the electronic device 100 moves from a coverage area of one Wi-Fi Access Point (AP) 200a to another Wi-Fi AP 200b, the current implementations try to perform the W2L and L2W handover instead of a direct W2W handover. In FIG. 1, electronic device 100 is not geographically within LTE coverage area 300. Since VoWiFi is intended to extend benefits of VoLTE to the user of the electronic device 100 when cellular coverage is poor or absent, requiring handover to an LTE base station (the current handover logic) fails to ensure a seamless user experience in some circumstances. The dropped connection of FIG. 1 includes disruption IMS services relied on by electronic device 100.
This related art handover approach lacks ability to address a wide range of issues which are listed as follows:                a) The VoWiFi to VoWiFi seamless handover is not feasible at places with no LTE coverage (for example, outside area 300 of FIG. 1). This is a severe shortcoming of existing methods. In the existing methods a break in an IMS session can occur whenever the LTE coverage area 300 is not available. Then, the IMS session needs to be re-established after electronic device 100 re-establishes a Wi-Fi connection. The call drop causes disruption in the IMS services. A disruption in IMS services can disrupt an active VoWiFi call; causing a bad experience for the user of the electronic device 100.        b) Poor user experience in a low LTE coverage area 300: In areas of low LTE coverage such as cell boundary regions, there may not be complete disruption of the IMS services. However, a user experience can be seriously impacted during the transition to LTE caused by multiple retransmissions, packet loss, and long mute events during a call. Typically, electronic device 100 has a mechanism to perform some basic performance checks before connecting to Wi-Fi. The basic performance checks cause delay in switching back to the VoWiFi from VoLTE, the delay results in a poor user experience.        c) Multiple handovers performed during VoWiFi-VoWiFi transition: By performing handover to the VoLTE, the number of handovers in current implementations is almost twice the number actually required. Since handover is an expensive operation in terms of the signaling bandwidth and involving resources at the electronic device 100 and network to be released and reallocated, excessive handover events correspond to a poor design and implementation.        d) Session break for all apps performing networking operation: Multiple session breaks for apps a generic problem observed in apps using some networking and not only related to the IMS sessions. Whenever, the electronic device 100 moves from the Wi-Fi to the LTE to Wi-Fi, applications listening for networking broadcasts will receive multiple connection and disconnection indications.        
In the existing related art methods, handover signaling activity has been carried within the IMS call handover context. There is a challenge to effectively address the underlying problem for any network architecture. On the other hand, there has been quite a lot of research in terms of heterogeneous handover decisions. In an example, many mechanisms have been presented regarding the probe-and-decision phase to reduce the original IEEE 802.11 probe latency from hundreds of milliseconds to tens of milliseconds (or even less). These mechanisms include guidelines for handoff schemes based on factors affecting overall handoff latency, use of neighbor graphs and non-overlap graphs to reduce total number of probed channels and total time spent waiting on each channel and to reduce scanning delay by selective channel scanning for fast handoff. In another existing method, a handoff procedure utilizes a selective scanning mechanism and a caching mechanism, which reduces a medium access control (MAC) layer handoff latency and selective neighbor caching scheme for handoff between the Wi-Fi access points (APs) 200a and 200b. The related art has not addressed VoWiFi-VoWiFi problems.
Thus, it is desired to address the above mentioned disadvantages or other shortcomings or at least provide a useful alternative.